Method of combatting pests by applying novel granules to the soil

ABSTRACT

Granules prepared by absorbing on hydrophilic polymer of acrylic acid polymers and/or acrylamide polymers granules an aqueous emulsion of at least one active principle such as pyrethrinoids and drying the resulting mixture to obtain granules which release the active principle in uniform manner.

PRIOR APPLICATION

This application is a division of U.S. patent application Ser. No.283,840 filed Dec. 13, 1988, now pending.

STATE OF THE ART

Related prior art includes German Patent Application No. 1,936,748,European Patent Application No. 0,201,214 and U.S. Pat. No. 3,329,702.

OBJECTS OF THE INVENTION

It is an object of the invention to provide novel granules useful in thephytosanitary field and the field of human and animal pharmaceuticals.

This and other objects and advantages of the invention will becomeobvious from the following detailed description.

THE INVENTION

The novel granules of the invention are prepared by absorbing onhydrophilic polymer granules an aqueous emulsion of at least one activeprinciple and drying the resulting mixture to obtain granules whichrelease the active principle in uniform manner.

The polymers used as the base for the granules are known products andhave been used, for example, as water retainers in agriculture, as mediafor in vitro culture, as media for pregermination of seeds, as separatewater reserves for plants, as fertilizer fixatives and as a medium formushroom culture. Examples of these granules are those sold under theTrade Mark AQUASORB® (acrylic acid, acrylamide copolymer 50/50) such asAQUASORB PR 3005 type A or PR005 type A of 2 to 3 mm granule size, orAQUASORB PR 3005 type B or PR005 type B of 1 mm granule size. Preferredgranules are those made up of polymers of acrylic acid or of acrylamide,or of polymers of acrylic acid and acrylamide.

The drying is preferably effected with talc such as LUZENAC talc whichacts both as a drying agent and as a lubricant, or any other agent whichfacilitates the fluidity of the granule.

The granules of the invention have the advantage of a simple and regularrelease of the active principle such as pesticides as can be seen fromthe test data infra.

Preferred granules are those prepared with an aqueous emulsioncontaining a solvent for the active principle(s), water, a cosolvent, asurfactant and a film-forming thickening agent. The amount of water isusually 25 to 60%, preferably 30 to 50% by weight of the composition.

The solvent used should have a low solubility in water, and must be agood solvent for the active material. For example, it can be a phthalatesuch as dimethyl, diethyl or dibutyl phthalates used on their own orcoupled with an aromatic-type solvent.

The surfactant used is generally a phosphoric ester. The phosphoricester is used in acid form or neutral form and it may be for exampleacid or neutral alkyl ether phosphates sold under the name AGRIMUL® DMF539 or under the name AGRIMUL DMF 395. It may also be phosphoric esteramine salts sold under the name AGRILAN F535 or Agrilan F546 or aphosphoric ester of ethoxylated nonphenol sold under the name BEYCOSTATQ A.

The cosolvent is preferably a diol such as propanediol. The film formingthickening agent is preferably a resin of polyvinyl alcohols and thefilm-producing agent used performs simultaneously the double functionsof thickening agent and of film-producing agent.

More preferred granules use an aqueous emulsion containing 1 to 5% ofactive principle, 30 to 50% of water, 10 to 30% of dimethyl phthalate, 0to 10% of phosphoric ester 5 to 20% of propandiol and 5 to 10% of apolyvinyl alcohol resin.

The active principle(s) are phytosanitary products such as pesticides,herbicides or plant growth regulators.

The pesticides used are preferably pyrethrinoids such as for exampledeltamethrin or also a product chosen from the group consisting ofpermethrin, cypermethrin, alphamethrin, tralomethrin, cyhalothrin,fenvalerate, cyfluthrin, flucythrinate, fluvalinate, fenpropathrin,tefluthrin and bifanthrin, as well as other derivatives of cyclopropanecarboxylic acid possessing biological properties.

The granules of the invention are interesting, for example forcombatting parasites sensitive to the active principles used. Theyimprove the persistency of action and regularity of activity and theyare particularly effective in combatting insects, acariens andnematodes.

When used in the phytosanitary domain, the granules of the invention canbe spread over the soil with agricultural machines and then mixed intothe soil. The granules are then placed under various irrigation systems,either natural (rain), or artificial whereby they will then store up thewater. As the soil dries out, the granules will put back this water andas well as the phytosanitary formulation by capillary action. This cycleof successive retentions and releases can be repeated several times.These impregnated granules, which are easy to make, are an ideal type offormulation adapted to the treatment of soil. They offer two advantages,namely an ensured protection of the active material and an availabilityof the latter.

In the following examples there are described several preferredembodiments to illustrate the invention. However, it is to be understoodthat the invention is not intended to be limited to the specificembodiments.

EXAMPLE 1

Granules were prepared by mixing a solution containing 30 g ofdeltamethrin, 270 g of dimethyl phthalate, 50 g of AGRIMUL DMF 539®(alkyl ether phosphate) and 5 g of ethylhydroxyethyl cellulose (EHEC)with a solution containing 65 g of MOWIOL 30/88®, 160 g ofpropanediol-1,2,1 g of citric acid and 419 g of softened water. Then,200 g of water were added to the resulting solution and the suspensionobtained was sprayed on to 300 g of Aquasorb granules to obtain ahomogeneous absorption of the solution. 120 g of talc were then added tothe granules thus obtained, and after mixing the desired granules wereobtained.

EXAMPLE 2

Granules at 0.025% were prepared with an aqueous formula containing 30 gof pentafluorobenzyl (1R,cis) 2,2-dimethyl-3-(2-fluoro-3-methoxy-3-oxo-1-(ΔE) propenyl)cyclopropane carboxylate,270 g of dimethyl phthalate, 50 g of Agrimul DMF 539®, 70 g of Mowiol4/88, 160 g of propanediol-1,2 and 420 g of softened water, 8.6 g of thesolution obtained were diluted with 40 g of water and then 73 g ofAquasorb granules were impregnated therewith. 8.8 g of a 25% solution ofBeycostat Q in methylene chloride were then sprayed onto the granules,20 g of talc were added, and after mixing, the granules sought wereobtained.

EXAMPLE 3

Granules at 0.8% were prepared using a composition containing 30 g oftefluthrin, 270 g of dimethyl phthalate, 50 g of Agrimul DMF 539®, 70 gof Mowiol 4/88, 160 g of propanediol-1,2 and 420 g of softened water, 27g of this solution were diluted with 40 g of water and then 62 g ofAquasorb granules were impregnated therewith. 8.8 g of a 25% solution ofBeycostat Q in methylene chloride were then sprayed onto the granules,20 g of talc were added, and after mixing the granules sought wereobtained.

BIOLOGICAL TEST

a) It was found that the granules of Example 1 very clearly improved thepersistency of action of deltamethrin on the insect SCOTIA SEGETUM. Itwas found that at a dose of 0.25 ppm of active principle, 45 days afterthe start of the treatment, the mortality rate was 45% and that a doseof 1.5 ppm of active principle, the mortality rate was 100%.

b) An excellent activity of the 0.05% deltamethrin granule was alsofound, whether it be immediate activity or activity after 50 days, withregard both to the SCOTIA SEGETHUM and GRILLUS DOMESTICUS species.

Various modifications of the compositions and method of the inventionmay be made without departing from the spirit or scope thereof and it isto be understood that the invention is intended to be limited only asdefined in the appended claims.

What we claim is:
 1. A method of combatting insects in a fieldcomprising applying to the field surface an insecticidally effectiveamount of the granules prepared by absorbing on hydrophilic polymergranules of at least one member of the group consisting of acrylic acidpolymers and acrylamide polymers an aqueous emulsion of 30 to 50% ofwater, 10 to 30% of dimethyl phthalate, 1 to 5% of active principle, 0to 10% of phosphoric ester, 5 to 20% of propanediol and 5 to 10% ofpolyvinyl alcohol resin, all precentages based on the total weight ofthe emulsion, and drying the resulting mixture to obtain granules whichrelease the active principle in uniform manner, wherein the activeingredient is deltamethrin.
 2. The method of claim 1 wherein thegranules are made of acrylic acid polymers.
 3. The method of claim 1wherein the granules are made of acrylamide polymers.
 4. The method ofclaim 1 wherein the granules are made of acrylic acid polymers andacrylamide polymers.